In theory, anyone can be an "appraiser" with suitable training or experience. Very few fields have a certification process. This is why slabbing services are suspect - they appraise, but might not have the level of expertise collectors, courts, and insurance companies might desire.

In short, an appraiser is an expert who assesses the value of an item. Court rules for allowing someone to testify as an expert witness are fluid - it must be shown that the person possesses specialized knowledge as a result of training or experience. There are many contributors to this website who would likely qualify as expert witnesses should the need arise, especially in specific areas (crest & seal, Atlantic City, California card rooms, etc.). Mr. Irving may be similarly qualified.

When someone says he or she is an appraiser, it is important to determine their level of training or experience rather than just relying on the title "Appraiser."